Isn't it odd that FBI still fails to understand that there may be a backup copy of privkey somewhere? They have not moved the coins to an address they created! I would breaking a drop of sweat per second...
Why do you say that? Where have you got this info from?
Assuming 1F1tAaz5x1HUXrCNLbtMDqcw6o5GNn4xqX was under DPR's control before he got arrested, it is likely he's got backup copies of the corresponding private key somewhere. We all back up our wallets, right? Multiple copies of paper wallets in different locations? Brain wallet? Somebody else may get hold of a copy of this private key (which was supposedly sitting unencrypted on one of the imaged servers), or DPR may covertly pass on the private key to someone. FBI and prosecutors might wake up one morning just to find out that their "seized assets" have disappeared from their custody because they were too lazy to read and understand how Bitcoin works.